1. Field of the Invention
The present invention relates to the field of audio/video processors, storage devices and servers, and more particularly, to random access audio/video systems.
2. Art Background
Video editing systems have evolved from providing simple editing cuts to the incorporation of full feature graphics, film-to-tape, and other processes to complete a video production. Non-linear random access video editing systems permit access to any video frame from any location on the storage media and rearrangement of the frame into a desired output. The coupling of computer technology with video tape editing systems, as well as multimedia hardware and software support, including, by way of example, CD ROM technology, magnetic storage media and graphic user interface technology, permits the editor to incorporate and integrate various production media resources such as special effects, music, graphics, and the like into a production.
One of the requirements of any multimedia video/audio editing system is to provide the operator with the ability to manage large quantities of information in an understandable and efficient manner. The system must be flexible and intuitive, to accommodate a variety of operator editing styles and personalities. Various video tape editing systems have been developed in the past, for example the Sony DNE-300 manufactured by Sony Corporation of Tokyo, Japan.
In video editing systems, a user requests that a number of audio/visual segments be displayed in a particular order. The limits on memory access time causes problems in prior art video editing systems. In particular, any type of memory, especially on media such as hard and floppy drives and CD ROMs, employed by video editing systems requires time to fetch different segments. For any segment, the system must fetch the next segment before the current segment is completely displayed. Otherwise, there will be a gap between the display of the first segment and the display of the second segment while the system is reading the next segment. This gap may be unacceptable to users who desire uninterrupted audio/video playback.
Short segments in particular may cause such gaps because the system may not have enough time to fetch the material of the next segment before it finishes reading the material of the short segment. The amount of time required to fetch the material of a next segment is known as the threshold length; any segment shorter than the threshold length will cause a gap.
Prior art systems will either refuse to replay a sequence containing short segments (displaying an error message to the user), or else they display these segments with noticeable and unacceptable gaps following them. The present invention is a random-access video editing system designed to play back a sequence containing one or more short segments without any gaps.